Since hair is daily exposed to physical stimulation by daily hair care routines such as heat drying with a hair dryer and brushing, and chemical stimulation by shampooing, permanent weaving, dyeing and bleaching, it is in a damaged state with a partial loss of components or structure. A change in hair quality due to ageing accelerates this damage and also causes the loss of suppleness which healthy hair inherently possesses.
It is a common practice to protect or repair hair in a damaged state by making up for the lost components or structure or analogue thereof. Interaction (affinity) between a protecting base and hair is considered to be important for developing a protecting or restoring function, and thus a method of using a sphingolipid or protein derivative as a protecting base has been used widely as a useful technique. For example, proposed is a cationic dispersing agent for hair care or hair protection containing a ceramide or glycoceramide and a specific quaternary ammonium compound (Japanese Patent Application Laid-Open No. 502660/1994). The agent however cannot contain a sufficient amount of a protecting base such as a ceramide or glycoceramide because it has a high melting point and is liable to crystallize. Moreover, this protecting base, through added in a slight amount, does not readily penetrate into hair. The conventional hair cosmetic composition is therefore accompanied by the problem that the protecting base incorporated therein cannot fully function, because it cannot be fed to hair in an adequate amount.
In addition, it is difficult to incorporate the above-described protecting base stably in the hair cosmetic composition because it has a high melting point. There is also a problem that the protecting base is liable to cause separation, gelation or crystallization with the passage of time.